Apparatus for casting metal tubing by continuous process



R. BUCCJ hm. fi, mm

APPARATUS FOR CASTING METAL TUBING BY CONTINUOUS PROCESS 3 Sheets-Sheet 1 Filed Dec. 18, 1967 INVENTOR. FOBEQT BUCCI Jan. fi, 1970 R. BUCCI APPARATUS FOR CASTING METAL TUBING BY CONTINUOUS PROCESS Filed Dec. 18, 1967 3 Sheets-Sheet 2 INVENTOR.

BY m

.flmmfi, 1970 R. BUCCI 3,487,876

APPARATUS FOR CASTING METAL TUBING BY CONTINUOUS PROCESS Filed Dec. 18, 19s? a Sheets-Sheet 3 mvzzmon Roam-r 50cm E v Q 2 00\ I U u SAN United States Patent US. Cl. 164263 6 Claims ABSTRACT OF THE DISCLOSURE The specification shows and describes apparatus for making seamless tubing by a continuous casting method as distinguished from the prior art method of making tubing by essentially an extrusion operation. The metal is poured into rotating molds and the formed tubing is also rotated during the molten and chilling stage while it is drawn down continuously and cut to measured lengths. As the formed tubing is rotated, the molten metal in the forming or matrix area will continue to solidify at the rate determined by the chilling action of the mold walls. The invention further contemplates the use of a frusto-conical shaped inner mold in which the tubing will be rotated and drawn away from the molding area, the taper extending between the molding and cooling areas.

The apparatus utilizes universal chucks for gripping and releasing the tubing as it is being formed to draw it downward and to hold and rotate the formed tubing while it is subjected to the action of a cutoff tool to form a tubing of a given length.

The invention will become more apparent from a consideration of the accompanying drawings constituting a part hereof in which like reference characters designate like parts and in which:

FIGURE 1 is a vertical cross-sectional view, partially in elevation, of the top or forming portion of a continuous tube casting machine embodying the principles of this invention;

FIGURE 2 is a similar view of the bottom portion of the casting machine shown in FIGURE 1;

FIGURE 3 is a vertical cross section of the bottom portion of the stripper chuck at the start of the pouring operation;

FIGURE 4 is a similar view showing the position of the stripper chuck and tube rotating chuck during the cutoff of the imperfect taper portion on the cup;

FIGURES is a similar view showing the cutoff of the finished tubing;

FIGURE 6 is a diagrammatic illustration of the universal chuck jaw and actuator; and,

FIGURE 7 is a section taken along the line 7--7, FIGURE 6.

With reference to FIGURE 1 of the drawing, the numeral 1 designates a fixed housing wall supported on a casting 2 mounted on a platform 3 or other suitable support. Disposed within the housing is an outer mold wall designated by the numeral 4. A cooling chamber divided by partitions 5 and 6 is constituted by the space between the housing wall 1 and the outer mold wall 4. A cooling fluid is supplied to the cooling chamber by a pipe line 7 connected to a cooling chamber 11 having an outlet for the cooling fluid at 8, the fluid flows downward, as shown by arrows, to and around the open end of stationary partition wall 6, thence upward to an outlet tube 9, circulation of the fluid being controlled by a motor driven pump 10. The outer mold wall 4 and the partition member 5 are mounted on a supporting ring 3,487,876 Patented Jan. 6, 1970 12 that is mounted on anti-friction bearings 13 to be rotatable by means of a gear drive 14 shown at the upper lefthand side of FIGURE 1. The outer mold wall 4 is provided with a flange 15 having gear teeth 16 that interact with the teeth 17 of a drive pinion at the end of shaft 18, the pinion shaft being provided with a gear wheel 19 engaging a pinion 20 on the shaft of a drive motor 21.

Disposed within the tubular space inside of the outer mold wall 4 is an inner mold wall 23 which is tapered at the bottom to form an inverted frusto-conical shape, as shown at 24, the mold having a closed bottom 25 and a closed top or cover 26. The conical shape of the inner wall 23 prevents molded tubing from grippingly engaging the mold wall while shrinking. A liner of high refractory metal such as stainless steel or carbide is provided, as shown at 23a at the upper portion of the inner mold wall 23. Disposed Within the mold 23 is a tube 27 having a flanged bottom 28 that constitutes a baflle for the flow of fluid that is supplied through an inner tube 29, the fluid flowing as shown by the arrows, and escaping through the space between tubes 27 and 29 to a pipe coupling 30 having an inlet pipe 31 that is connected to the center tube 29 and an outlet pipe 32 that is connected to the baffle tube 27, the flow being diagrammatically shown by the lines and arrows as leading to the pump 10. The inner mold 23 is driven by the inner mold shaft 34 that is supported on roller bearings generally designated by the numerals 35 and 36, the shaft 34 having gear wheels 37 with teeth 38 that interact with the teeth of a pinion 39 that is mounted on the drive shaft 18 that is driven by motor 21. It will be noted that the pinion and gear connections of the outer mold wall 4 and the inner mold 23 are such that they will revolve in the same directions. A flow spout 40 extends from a hopper 42 into which molten metal designated by the dotted lines 43, is poured from a molten metal carrying ladle 44 to a maximum level shown at 45, as shown in drawing. The outer mold wall may be provided with thermocouples 46 to operate valves (not shown) to control the volume flow of the coolant through the mold chambers to maintain a suitable chilling temperature throughout theflength of the mold walls.

The molten section of the poured metal shown as dot and dash lines is of approximately the temperature of molten steel at 2800 F. The stippled area shows the metal solidifying at about 1600 F. and the cross-sectional area from below the mold line 23a is at room temperature. The temperatures vary with the kind of metal poured.

Mounted on the flanged casting 2 is a universal chuck generally designated by the numeral 48. This will be hereinafter referred to as the upper or first chuck, the function of which is to engage the cast tubing shown in dotted lines and designated by the reference character 50, the tubing being engaged by jaws 51 of the chuck more clearly shown in FIGURES 6 and 7. The chuck is journaled by anti-friction bearings 52 and its flange 53 is provided with gear teeth 54 that are engaged by the pinion 55 mounted on drive shaft 56 of a motor 57. The jaws 51 of the chuck are advanced and retracted by motors 60, FIGURE 6, that operate a worm shaft a extending from a gear reducer 61, the chuck jaws being mounted in a square-shaped chuck block 58 that prevents rotation of the jaws 51 but permits the same to be advanced axially to engage the tubing 50 or be retracted to disengage the same. The motor 60 is connected by electrical conduits 62 through brushes 64 to slip rings 63 that are mounted on the gear 53 and the motors 60 operating the chuck jaws 51 can be energized to actuate the jaws to their closing and opening positions. Mounted on a slide 65 is a cutoff tool 66 operable by a piston in an air cylinder 67, the cutoff tool being shown in dotted lines in its cutting position in which it cuts off initially the tapered portion formed when the pouring of the molten metal is begun and subsequently the lengths of the finished tubing 50, as will be hereinafter explained.

With reference to FIGURE 2 of the drawing, the lower section of the casting machine consists of a chuck 88 and lift assembly mounted in a housing 70 based on a flange support 71 which may be anchored in a concrete foundation, as shown at 72. The housing 70, which may be of cylindrical shape, is in fact a hydraulic cylinder having a smooth inner wall 73 which is engaged by sealer rings 74 of a piston 75 which has a smooth outer surface 76 that engages the sealer rings 77 of an end ring 78 which is fastened to the housing 70 by screws 79. The piston 75 is operated by fluid pressure supplied through pipes 80 and 81. The fluid, while under pressure, is subjected to oscillating movement by a pump 82 operated by motor 83. The piston 84 of pump 82 is connected to an adjustable cam 83a to vary the stroke and hence the oscillating movement of piston 75 and the molded tube 50. The piston cylinder 75 is held against rotation by an antirotating blade 85 that is secured to the base 71 and the cylinder 75 is provided with a lug 86 that engages the blade 85 to prevent its rotation.

Mounted on the lifting cylinder 75 is the lower chuck assembly generally designated by the numeral 88, which is secured by bolts 89 to the top of cylinder 75. Disposed within a separate cylinder chamber 90 of the lifting cylinder 75 is a stripper piston 91 that engages seals 92 in the intured flange 92a of piston cylinder 75 and is provided with sealer rings 93 that engage the walls 94 of the upper piston chamber. The piston 91 is subject to movement in its cylinder by hydraulic pressure supplied through pipes 96 and 97.

Mounted on cylinder 91 is a cup 100 that supports the lower end of the casting tubing 50, as shown in FIGURE 3, when the molding of the tubing begins. The chuck assembly 88 is provided with the same chuck mechanism as described in connection with upper chuck 48 of FIG- URE 1 of the drawing. It is provided with jaws 101 that are secured in a chuck mount 102 in which a chuck block 58 of FGURE 6 is mounted. The chuck block that carries the jaws 101 is axially movable by means of a worm blank, FIGURE 6, actuated through a gear reducer by motors 103 which is connected to collector rings 104 in a power circuit. The chuck is rotatably mounted by antifriction bearings 105 and a gear ring 106 is driven by a pinion 107 operated by motor 108. The operation of the continuous tube casting apparatus will now be described in connection with FIGURES 3, 4 and of the drawings.

With reference to the cup 100, it is mounted on the stripper piston 91 and in FIGURE 3 of the drawings, it is shown as raised to its upper limit by the lift assembly cylinder 75. The inner mold 23 is shown surrounded by the cast metal to form the end of the cast tubing 50. In this position, the upper chuck 48 is opened and stripper piston 91 is lowered by supplying fluid pressure through the duct 96, FIGURE 2. As the cup 100 drops, the end 50a of tubing 50 will drop to the area of function of the lower chuck 88, which is energized to close the chuck jaws 101 to engage the tubing 50a. Motor 108 is energized to rotate chuck 88. The lifting cylinder 75 is then lowered, as shown in FIGURE 4 of the drawing, to cut off the tapered wall portion of the end of the tubing 50a by the cutoff knife 66, as shown. Before this is done, chuck 48 is operated to close the jaws 51, which engage the finished tube 50 and retain it in position while the cylinder 75 is lowered and the scrap piece 50a removed from the cup. The cylinder 75 in FIGURE 5 is again raised and the lower chuck 88 is closed to grip the end of the tubing 50. Cylinder 75 is then lowered by control of the fluids in ducts 96 and 97 to draw down a piece of tubing of predetermined length, which is cut off by the cutter 66, as shown in FIGURE 5. Once the initial scrap piece 50a has been removed, the casting operation will be continuous in the forming of the finished tube sections 50 without any intermediate cut-off of any scrap pieces.

As is evident from FIGURE 1 of the drawing, the shrinking area, which is the tapered portion 24 of the inner mold 23, prevents adhesion of the cast tubing to the inner mold wall, the shrinkage being effected by the coolant acting on the outer mold wall 4. The solidification of the tubing 50 causes the chuck 88 on the stripper to be rotated by motor 108 and the tubing is drawn down to a measured length, at which point the stripper piston 75 and piston 91 are stopped. In the cut-off position of the finished tubing, both chucks 48 andv 88 are closed and rotate in the same direction with the tubing atthe same rate of speed. When the finished piece has been cutoff, the upper chuck 48 continues engaging-the tubing andto rotate the same to keep it from sticking to the mold wall. The oscillating cam causing piston or cylinder 75 to oscillate vertically, also prevents the tubing from sticking to the mold wall and the continuous rotating and oscillating action keeps the tubing free from the molds.

While the tubing is cut off as described, the pouring of the molten metal may be reduced, but not stopped, to avoid forming a stop-starting line in the tubing, and the molten metal must be cooled at the very same spot in the molding area to ensure tubing of a uniform diameter.

It is evident from the foregoing description that the method of continuously casting seamless metal tubing which can subsequently be subjected to die drawing operations to obtain a desired finish on the inner and outer walls of the tubing eliminates the costly reheating and handling steps in the piercing operation in forming of seamless tubing by conventional die drawing and rolling methods.

It is also evident that modifications may be made in the design of the apparatus without departing from the priciples herein set forth.

I claim:

1. Apparatus for continuously casting seamless tubing of molten metal consisting of spaced inner and outer cylindrical mold walls, the outer mold wall being mounted for rotation on a rotary table and the inner mold wall being suspended from a rotary head,

means for rotating said table and head in the same direction,

cooling chambers for said mold walls and means for circulating a liquid coolant in said chambers to control the rate of solidification and density of the formed tubing,

a first chuck for gripping the end of the formed tubing mounted on said rotary table and a second chuck mounted on a lifting piston cylinder for engaging said formed tubing,

means for rotating said chucks in the direction of rotation of said tubing,

and cut-off mechanism beneath said first chuck for severing said formed tubing to predetermine lengths,

the speeds of said mold rotating and lifting devices being regulable to control the density of the metal in the formed tubing.

2. Apparatus as set forth in' claim 1 in which,

a cup for initially supporting the formed tubing is removably mounted on the piston cylinder.

3. Apparatus as set forth in claim 1 in which,

the cup for supporting the formed tubing is mounted on a stripping cylinder,

and in which the piston cylinder is subjected to oscillating movement to prevent adhesion of the formed tubing to the mold walls.

4. Apparatus as set forth in claim 1 in which,

the inner mold wall is tapered inward along the axis thereof to cause the inner wall of the formed tubing to sag away from the mold wall.

5. Apparatus as set forth in claim 1 in which,

the first and second chuck are independently operable,

and the first and second chucks are in engagement with the formed tubing when the cut-off mechanism severs the said tubing.

6. Apparatus as set forth in claim 1 in which,

the lifting piston cylinder is restrained from rotary movement at all times,

and the spacing of the piston cylinder and the cut-off mechanism determines the length of the cut-01f tubing.

References Cited UNITED STATES PATENTS 1,223,676 4/1917 Lavaud 164-282 6 2,408,514 10/1946 Hazelett 164-85 2,752,648 7/1956 Robert 164-263 3,268,959 8/1966 Babel et a1 164-85 X FOREIGN PATENTS 960,126 3/ 1957 Germany.

569,367 11/1957 Italy.

10 J. SPENCER OVERHOLSER, Primary Examiner R. SPENCER ANNEAR, Assistant Examiner US. Cl. X.R. 

